diff --git a/os/rt/ports/ARMCMx/cmsis_os/cmsis_os.c b/os/rt/ports/ARMCMx/cmsis_os/cmsis_os.c
index 30174405f..df4b6ba31 100644
--- a/os/rt/ports/ARMCMx/cmsis_os/cmsis_os.c
+++ b/os/rt/ports/ARMCMx/cmsis_os/cmsis_os.c
@@ -487,7 +487,7 @@ osMessageQId osMessageCreate(const osMessageQDef_t *queue_def,
                  queue_def->items,
                  (size_t)queue_def->queue_sz);
 
-  return osOK;
+  return (osMessageQId) queue_def->mailbox;
 }
 
 /**